Vertical etchers for minute parts

ABSTRACT

A vertical etcher is provided having means for controlling the angular velocity as well as the linear velocity of a part as it passes through a multiple nozzle spray etching chamber. Further means are included for spacing and adjusting the enchant spray nozzles to produce a uniform spray of etchant over the part to be etched as well as etchant wipers located at the entrance and exit to the etchant chambers to stop the etching action as quickly as possible.

March 5, 1974 H. M. BOND ErAL VERTICAL ETCHERS FOR MINUTE PARTS FiledJuly 24, 1972 LO lf) 3 Sheets-Sheet l March 5, i974 H. M. BOND ErAL3,795,561

VERTICAL ETCHEHS FOR MINUTE PARTS 5 Sheets-Sheet 2 Filed July 24, 1972March 5, 1974 H, M BOND ETAL VERTICAL ETCHERS FOR MINUTE PARTS 3Sheets-Sheet 5 Filed July 24, 1972 o U i m\.\U

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United States Patent O 3,795,561 VERTICAL ETCHERS FOR MINUTE PARTSHerbert M. Bond and Michael E. Rucinski, St. Paul, Minn., assignors toBuckbee-Mears Company, St. Paul,

inn.

Filed July 24, 1972, Ser. No. 274,346 Int. Cl. C23f 1/02 U.S. Cl.156-345 12 Claims ABSTRACT OF THE DISCLOSURE A vertical etcher isprovided having means for controlling the angular velocity as well asthe linear velocity of a part as it passes through la multiple nozzlespray etching chamber. Further means are included for spacing andadjusting the etchant spray nozzles to produce a uniform spray ofetchant over the part to be etched as well as etchant wipers located atthe entrance and exit to the etchant chambers to stop the etching actionas quickly as possible.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates generally to etching machines and more specifically, to verticalspray etching machines for uniformly etching small and minute parts.

Description of the prior art Vertical etchers and vertical etchingmachines are known in the prior art and have been used for some time inthe etching of moving webs. Typical etchers of this type are shown inMears Pat. 2,762,149 which shows a vertical etcher for etching elongatedwebbing in which the nozzles are spaced along the header. The nozzlesare stationary and the web moves horizontally through the verticaletching machine so that the etchant impinges on the web at right angles.

Another embodiment of a vertical etching machine for Webs is shown inthe Mears Pat. 2,822,635 which shows another vertical etcher for sprayetching a web that moves horizontally at a continuous rate through anetching chamber. The nozzles in this latter vertical etcher oscillateabout a central axis during operation to alternately direct the etchantupward and downward. In addition, 'an upward and downward velocity isimparted to the nozzles so that the nozzle spray scans the web duringthe etching process. One of the problems of spray etching a web is thatareas or pockets of localized passivity occur which affects the iinaldimension of the etched article. This problem is virtually eliminated inthe aforementioned Mears patents, which are assigned to the sameassignee as the present invention, by directing a high velocity sprayalternately upward, downward and vertically across the web surface. Inaddition, nozzle motion prevents the lodging of minute gas bubbles whichform during the etching reaction in the web aperture. The localpassivity and lodging of gas bubbles are one of the principal causes ofnonuniform etching where the concentration, the temperature of theetchant and distribution of the etchant orver the area to be etched areunder proper control. Thus, by adjusting the angle of oscillation of theseveral nozzles, one can obtain reliable and uniform results with theapparatus shown in the Mears patents. However, one uncompensateddrawback exists in the use of vertical etchers such as Mears is theinfluence of the gravitational field on the etchant liuid. That is, theetching uid after impinging on the part begins to run to the bottom ofthe part. While for ,some operations such as etching metal webs, theoveretching produced by rundown is so minimal, it can be compensated foror tolerated, it is not always possible to tolerate or compensate foroverice etching produced in etching operations on precision etched itemsrequiring tolerances of less than .0005 inch. Therefore, it is necessaryto have some means of controlling the etchant spray to obtain a uniformspray over the entire surface of the article to be etched as well ascontrolling the etchant runoff. This is particularly true with articleswhich are to be etched from both sides and which vary considerably inareas to be etched. The present invention is an outgrowth of the problemof providing a vertical etcher for etching small or large parts whicheliminates irregularities in etching due to nozzle spacing,gravitational fields, over-exposure and nozzle spray patterns.

BRIEF SUMMARY OF THE INVENTION Briefiy, the present invention comprisesa vertical etcher in which one controls the angular velocity of the partto be etched, the linear velocity of the part to be etched, theIvertical velocity of the nozzles, the vertical nozzle spacing and thehorizontal spacing of the nozzles -from the part to be etched. Inaddition to nozzle spray pattern control, llow meters and valves areprovided to increase or decrease the amount of etchant impinging on thearticle as well as the momentum of the etchant impinging on the article.Furthermore, a pair of similar etching chambers and etching nozzles areprovided in order to provide iiner control and adjustment of the sprayetchant. Other features of the invention will be described in thedescription of the preferred embodiment of the machine.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a front elevation view of myvertical etching machine;

FIG. 2 is a side elevation view of the vertical etching machine;

FIG. 3 is a cross-sectional view of the oscillating and adjustingmechanism for the nozzle supply;

FIG. 4 is a side elevation view of the holder for holding the article tobe etched as it passes through the vertical etching chambers; and

FIG. 5 is an end view partially in schematic showing the vertical etcherpart support ring as it fits into a track and guides which propel thearticle to be etched through the various etching and rinsing chambers.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. l and 2,reference numeral 10 generally designates a vertical etching machine.Vertical etcher 10 comprises a first etching chamber 11, a secondetching chamber 12 and a rinse chamber 13. As etching chamber 11 andetching chamber 12 are identical, only one of the chambers will bedescribed Kwith respect to the vertical etching machine 10. Etchingchamber 12 contains a supply header 14 which is mounted horizontally inchamber 12. Supply header 14 is connected to a source of etchant fluidunder pressure while one end of header 14 is rotatably mounted in ahousing 15 and the other end of header 14 is rotatably mounted in asimilar housing (not shown). Housing 15 is mounted on a first threadedrod 16 and a second threaded rod (not shown) and is fastened in ahorizontal position on the threaded rods by double nutting flange 15a tothe two threaded rods. Similarly, supply headers 17, 18, 19 and 20 aremounted and fastened to a rst threaded rod 16 and a second threaded rod(not shown) by identical housings and fianges and therefore will not bedescribed. The mounting of supply headers 14, 17, 18, 19 and 20 onthreaded rods allows for vertical adjustment of the spacing betweenheaders to thereby control the spray pattern and the amount of etchantsprayed on an article to be etched.

Referring to FIG. 3, supply headers 14, 17, 18, 19 and 20 are shown incross-sectional View with sets of nozzles 14a, 17a, 18a, 19a and 20alocated thereon. 'Each set of nozzles is connected to headers and spraysetchant toward an article to be etched which would be located verticallybetween the two banks of supply headers. Located on the opposite side ofheaders 14, 17, 18, 19 and 20 are a similar bank of headers 21, 22, 23,24 and 25 which respectively have sets of nozzles 21a, 22a, 23a, 24a and25a. It should be noted that some of the nozzles 21, 22, 23, 24 and 25are illustrated positioned downward and some nozzles are positionedupward rather than perpendicular to an article to be etched. The variouspositions of the nozzles on the headers is for illustrating staticpositioning of nozzles by rotating a header. For example, an operatorcan adjust the orientation of the spray nozzle set 21a to spray upwardby rotating header 21 clockwise. This feature provides static control ofnozzle orientation as opposed to dynamic oscillation positioning inprior art devices. This static adjustability allows one to eliminateirregular spray patterns on the article to be etched through adjustingthe nozzles before etching. For example, suppose an article is to beetched more on the periphery than in the center. The operator thendirects the nozzles upward so the main thrust of etchant impinges on theperiphery of the part to be etched.

Located on the bottom of threaded rod 16 and threaded rod 29 is anotheradjustment rod 30 having a plurality of fastening members thereon forholding threaded rod 16 and threaded rod 29. Similarly, located on thetop of threaded rod 16 and threaded rod 29 is another threadedadjustment rod 34. By loosening nuts 31 and 32, one can position thebottom of threaded rod 16 inward or outward by securing nuts 31 and 32to the L-shaped member 44. Similarly, nuts (not shown) are located onthreaded adjustment rod 34 to provide adjustment of the top of threadedrod 16. With this conguration the supply headers can be moved in or outby adjustment of the position of nuts on threaded adjustment rod andthreaded adjustment rod 34. Similarly, the opposite supply headers havemeans for adjusting and positioning inward also.

FIG. 3 also shows a rectangular or support frame 35 for the banks ofetching headers which are connected to rod 30 and rod 34. Member 35includes a cam follower 36 which is rotatably mounted in a housing 37.Cam follower 36 operates in conjunction with a cam 38 (FIGS. 1

Vand 2). Rotation of a cam shaft 39, which is driven by a motor 40 and asuitable gear reducing mechanism y41, causes cam 38 to rotate thusforcing cam follower 36 and frame to follow the surface of cam 38. Theparticular cam shown is a constant velocity cam and provides a uniformupward and downward velocity of the member 35 with a constant rate ofrotation of shaft 39. Thus, the vertical motion transferred to member 35causes the nozzles and the spray to sweep up and down at a constantvelocity within etching chambers 11 and etching chamber 12. This featureof the oscillation of the supply headers and the nozzles at a uniformvelocity provides a uniform sweeping spray of the etchant onto thearticle or part to be etched.

Referring to FIG. l, the article to be etched is designated by referencenumeral 50 and is attached to a circular holding member 51 which has anopening S2 therein. The article to be etched generally is of a type thatrequires uniform etching from both sides. In order to etch from bothsides, one fastens article 50 over opening 52 in circular member 51.Circular holding member 51 has a set of teeth 51a thereon which formmating engagement with a continuous lower drive belt 54 and an uppercontinuous drive belt 55. Upper belt 55 continuously contacts thetopmost portion of ring 51 as it passes through the etching chamberswithin a track 56 which passes through etching chamber 11, etchingchamber 12 and rinse chamber 13. Upper drive belt 55 passes around awheel 62 and around a power driven wheel 57 which is connected to motor58 by a suitable variable speed drive mechanism (not shown). Similarly,lower drive belt 54 passes around a wheel 63 through etching chamber 11,etching chamber 12 and rinse chamber 13 in a track guide 60. Belt 54then continues around a power driven wheel 61. Wheel 61 is driven by amotor 59 and a variable speed drive mechanism similar to the mechanismdriving upper belt 55 (not shown).

In order to illustrate the operation and function of holding member 51,reference should be made to FIG. 4 and FIG. 5 which shows a portion ofthe section for guiding and holding wheel 51 in an upright position.Upper drive belt 55 and lower drive belt 54 are shown engaging the upperportion and lower portion of wheel 51. To keep wheel 51 `from fallingover, there is provided a pair of lower guide member 70 and 71 whichsubstantially encase track 54 and a similar pair of upper guide members72 and 73 which substantially encase track 55. These guide membersmaintain circular article holder 51 in a vertical orientation as itpasses through etching chamber 11, etching chamber 12 and rinse chamber13.

The two drive belts 54 and 55 are controlled by separate variable speeddrive mechanisms so that the linear velocity of the two tracks as Wellas the direction of rotation of the two drive belts can be independentlycontrolled. Thus, because article holder 51 will be driven by belt 54and belt 55, one can control the angular velocity as well as the linearvelocity article holder 51 takes in its journey through etching chamber11, etching chamber 12 and rinse chamber 13. For example, if belt 55 andbelt 54 are rotated at the same velocity and in opposite directions,article 50 on circular member 51 will pass through the etching chamberin the same orientation as it enters without any angular velocity.However, by maintaining a slight differential linear velocity or slowingdown, stopping, or even reversing the direction of one drive belt willrotate article holder 51 as it passes through the various chambers. Infact, with the rates of rotation of the drive belts constant but in thesame direction, the article holder 51 will have only angular velocity.That 1s, one can cause article holder 51 `to rotate in one position muchin the same manner as if it was attached to a rotating shaft.

While the various components of the etching apparatus have beendescribed, the operation of the etching appa ratus in conjunction withan article holder will now be described. Briey, in operation of verticaletcher 10, one rst powers drive belts 54 and 55 at predetermined speedand direction so that article 50 enters etching chamber 11 through adoor 80 and a door 81 which have a wiper ap 82 and a wiper ap 83respectively connected thereto. Wiper aps 82 and 83 are preferably madefrom a rubber-like or pliable material to produce a squeegee type wipingon the surface of the article as it enters chamber 11. In addition towiper flaps 82 and 83 at the entrance of the chamber, there is a pair ofwiper flaps (not shown) located between etching chamber 11 and etchingchamber 12, a pair of wiper flaps l(not shown) between rinse chamber 12and etching chamber 13 and a air of wiper tlaps (not shown) at the exitof rinse cham- When article 50 and article holder S1 enter etchingchamber 11, a spray of etchant from spray nozzles located on the headerssweeps across the article thus etching the article. As article 50 leaveschamber 11, the Wiper aps (not shown) located between chamber 11 andchamber 12, wipe off any excess etchant. After leaving etching chamber11 article 50 enters a second etching chamber 12 where it is similarlysubjected to a spray of etchant from a second set of sweeping spraynozzles.

After etching article 56 in chambers 11 and 12, article 50 passesthrough wiper flaps (not shown) to remove any excess etchant. Next,article 50 enters a rinse chamber 13 which has spray nozzles 85 thereinwhich spray water onto article S1 thus rinsing and diluting the etchantto prevent any further etching due to etchant on the article. Theinitial stopping of the etching action is provided by the squeegeeaction or wiping action of the iiaps located at the exit to etchingchamber 12. However, to ensure a complete stopping of the etchingaction, one should immediately rinse the article with water to removeany excess etchant.

Thus, in operation of vertical etcher 10, an operator places the articleto be etched on the circular member 51. Next, motors 58 and 62 areactivated to begin rotation of drive belt 54 and drive belt 55. Bycareful selection of the rotational velocities of drive belts 55 and 54,the operator can preselect the angular velocity and the linear velocityof the article 50 as it passes through etch- 1 ing chamber 11 andetching chamber 12. This feature, in essence, allows one to control thetime of etching without the aid of a timer as well as prevent etchantrundown. The article enters chamber 11 and rotates as it passes throughthe etching chamber which eliminates any rundown or accumulation of anyetchant at the bottom of the part to be etched. However, to eliminateany spiral etched patterns on the article due to rotation of thearticle, we provide the aforementioned oscillating or vertical sweepingmotion to the spray etchant by means of frame 3S, cam follower 36 andconstant velocity cam 38. This control of the upward and downwardsweeping motion of the etchant as well as the angular and linearvelocity of the article to be etched provides a precision etching systemfor use in precision etching.

As a further modification, we can control the temperature of the etchantin the system by heaters 90, 91, 92 and 93 which heat the etchant andmaintain it at a constant temperature. Similarly, a set of valves andliow meters 101 through 105 are connected to supply headers 14, 17, 18,19 and 20 allow one to precisely control the amount of etchant ow aswell as to ensure that etchant is continually owing into the supplychamber and supply nozzles.

We claim:

1. An etching apparatus for etching articles which are locatedsubstantially in a vertical plane comprising:

an etching chamber;

a plurality of etchant plenum chambers located in said etching chamber,a plurality of etchant spray nozzles attached to each of said pluralityof plenum chambers, each of said spray nozzles operable for directingetchant in a preferred direction;

means for positioning said plurality of spray nozzles in a verticaldirection, means for positioning said plurality of spray nozzles in ahorizontal direction;

means for adjusting the nozzles to control the preferred direction ofetchant ilowing from said nozzles;

means for oscillating said plurality of nozzles in a vertical direction;and

means for vertically mounting an article to be etched,

further means for propelling the means for vertically mounting anarticle to be etched through said etching chamber, said further meansincluding means for rotating the article to be etched as it passesthrough said etching chamber so that the article to be etched is sprayedwith etchant from said plurality of spray nozzles.

2. The invention of claim 1 lwherein said means for vertically mountingan article to be etched comprises a disc having a central openingtherein.

3. The invention of claim 2 wherein said disc has a set of teeth thereonfor engaging a drive belt.

4. The invention of claim 3 wherein said means for rotating the articleincludes a rst and second drive belt for forming mating engagement withsaid teeth on said disc.

5. The invention of claim 4 wherein said apparatus includes a rst andsecond variable speed drive mechanism or controlling the speed of saidfirst and second drive elts.

6. The invention of claim S wherein said means for oscillating saidplurality of nozzles in a vertical direction comprises a constantvelocity mechanism.

7. The invention of claim 6 wherein said etching apparatus includes aiirst etching chamber, a second etching chamber and a rinse chamber.

8. The invention of claim 7 wherein said apparatus inclules means forwiping excess etchant from the article to be etched.

9. The invention of claim 8 wherein said means for wiping excess etchantfrom the article to be etched are positioned between said rst etchingchamber and said second etching chamber.

10. The invention of claim 9 wherein said apparatus includes at leasttwo banks of spray nozzles positioned to direct etchant spray toward anarticle to be etched which is centrally located between said bank ofnozzles.

11. The invention of claim 10 including means for controlling thetemperature of said etchant.

12. The invention of claim 11 wherein a ow meter connects to each ofsaid plenum chambers.

References Cited UNITED STATES PATENTS 11/1972 Wessells et al. 156--345

